How to Build a Homemade Pond Filter System

Discover how to build a homemade pond filter system that is effective, inexpensive and very simple to make.

Biological Filter

There are many methods by which you can create a pond filter. An effective yet fairly simple application is an external biological gravel basin filter with an added U.V. sterilizing light. The biological filter breaks down ammonia produced by fish into safe useful fertilizer for pond plants. The U.V. Sterilizer kills pathogens, mosquito larvae, and parasites.

Items needed to build this type of filter include:

A large basin – it should be large enough to hold 5-10% of your pond volume. These are available from your local pond retailer.

Filter media. There is any variety of possible media including lava rock, bio-balls, gravel, or even nylon pot scrubbers. Fill the container about four fifths full with your chosen filter media.

A submersible water pump strong enough to circulate the entire volume of your pond in 60-90 minutes.

A U.V. Sterilizer light. If you’re working on a tight budget you may want to wait and add the U.V. Sterilizer as a later step.

A few water plants. Water hyacinth, yellow hornbeam, watercress, mint, or parrot feather are all good choices.

The Basin

First, the basin should be positioned so that it sits to one side of your pond, higher than the water level, ready to spill the cleaned water back in. Set it securely and be sure that you will be able to get to it to clean it once a year.

The Pump

Submerge the water pump into the pond, taking care to hook up the electric as per the manufacturer’s instructions.

U.V. Sterilizer

Run the hose from the submerged pump out of the pond and connect this to the U.V. Sterilizer. The light can be disguised with a housing to protect it from the elements and to make it more aesthetically pleasing.

Final Steps

Run a second length of hose from U.V. Sterilizer to the gravel filter, seating the hose securely into the filter media. Water should circulate through the media before spilling cleaned water out into the pond. Float plants directly into your filter for beauty and for added filtration.